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On the role of chiral catalysts in the alkenyl zirconocene/zinc addition to aldehydes: A study of ligand loading and asymmetric amplification
Author(s) -
Wipf Peter,
Jayasuriya Nilukshi,
Ribe Seth
Publication year - 2003
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10176
Subject(s) - chemistry , transmetalation , ligand (biochemistry) , aldehyde , enantioselective synthesis , chiral ligand , allylic rearrangement , catalysis , asymmetric induction , zinc , combinatorial chemistry , organic chemistry , receptor , biochemistry
Unusual nonlinear asymmetric amplification and chiral ligand loading effects were discovered for the use of catalytic quantities of chiral aminoalcohols in the in situ hydrozirconation—transmetalation—aldehyde addition processes. While the stereochemically most efficient aminothiol ligands demonstrated mechanistically conventional reaction parameters in excellent agreement with Kagan's ML 2 system, the asymmetric induction in the presence of a chiral aminoalcohol was found to vary greatly with loading and %ee of the ligand. Aminothiols remain the ligands of choice for the highly enantioselective formation of allylic alcohols and provide experimentally more predictable reaction variables. However, new, optimized conditions lead to a synthetically useful product %ee using the readily available and scalable aminoalcohol 2a. Chirality 15:208–212, 2003. © 2003 Wiley‐Liss, Inc.